柔性PDMS基介电复合材料的电场及击穿损伤形貌演变规律研究

doi:10.15541/jim20220326

摘要/Abstract

摘要：

与其它储能设备相比, 由介电复合材料制得的介质电容器在快速充放电能力与高功率密度方面极具优势, 如何提高介电复合材料能量密度与优化其击穿性能已成为当前研究热点之一。为进一步调控并兼顾介电常数与击穿性能, 本工作基于DBM(Dielectric Breakdown Model, 介电击穿模型), 采用有限元数值模拟, 研究了无机填料的分布对柔性聚二甲硅氧烷(PDMS)基介电复合材料体系的电场与发生介电击穿时击穿损伤形貌演变的具体影响。研究结果表明: 填料与基体边界处存在较大的介电差异, 可以使用较大介电常数的聚合物基体或较小介电常数的无机填料来减小其界面处的高电场区域, 继而提高复合材料的耐击穿能力；同时发现当无机填料分散更均匀时, 其树状损伤通道更容易产生分支, 此种情况将使介电击穿的树状损伤通道的损伤位点增多, 延缓其损伤速度, 继而提高复合材料的耐击穿性能。该研究结果将为开发高储能密度且具有优异击穿性能的有机-无机复合电介质材料提供坚实的理论依据。

关键词: 介电性能, 复合材料, 电场分析, DBM模型, 有限元法

Abstract:

Compared with other electric energy storage devices, dielectric capacitors made of dielectric composites have great advantages in fast charging and discharging capacity with high power density. A dilemma of improving the energy density of dielectric composites and synchronous optimizing their breakdown performance is becoming an intriguing research direction. To further adjust the contradiction between dielectric constant and dielectric breakdown performance, here a finite element numerical simulation based on dielectric breakdown model (DBM) was proposed to study the effect of the distribution of inorganic fillers on the electric field and breakdown damage morphology in flexible polydimethylsiloxane(PDMS) based dielectric composite system. The results show that a large dielectric difference is observed between filler and matrix, which indicates that polymer matrix with a large dielectric constant or inorganic filler with a small dielectric constant can realize reducing the size of the high electric field area at the interface and improving the breakdown resistance of the material. This study further reveals that the more dispersed structure of inorganic fillers, the more likely its dendritic damage channels tend to branch, indicating that this situation is conducive to the increase of damage sites of dielectric breakdown dendritic damage channels, the decrease of damage rate, and the improvement of breakdown resistance of materials. All above data demonstrate that this study provides certain guidance for the development of organic-inorganic dielectric composites with both high energy storage and excellent breakdown performance.

Key words: dielectric property, composite material, electric field analysis, DBM model, finite element analysis

中图分类号:

TB332

陈雷, 胡海龙. 柔性PDMS基介电复合材料的电场及击穿损伤形貌演变规律研究[J]. 无机材料学报, 2023, 38(2): 155-162.

CHEN Lei, HU Hailong. Evolution of Electric Field and Breakdown Damage Morphology for Flexible PDMS Based Dielectric Composites[J]. Journal of Inorganic Materials, 2023, 38(2): 155-162.

图/表 10

图1 填料在基体中的分布情况示意图

Fig. 1 Distribution of fillers in matrix

图2 尺寸为2 mm×2 mm的正方形介电复合材料模型

Fig. 2 Model of square dielectric composite with size of 2 mm×2 mm

图3 DBM模型的计算方法

Fig. 3 Calculation method of DBM model (a) Electric field distribution determined by finite element analysis; (b) Electric field distribution determined by MATLAB; (c) Two-dimensional array model consisting of 200×200 grid points Colorful figures are available on website

图4 改变填料与基体介电常数之比时, 介电复合材料电位移的变化

Fig. 4 Electrical displacement evolution of dielectric composite material with varied ratio n between fillers and matrix dielectric constant (a)When the dielectric composite filler is selected to be BaTiO3; (b) When the dielectric composite matrix is selected to be PDMS

图5 不同生长系数η时的树状损伤通道

Fig. 5 Dendritic damage channels with different growth coefficients(η) Colorful figures are available on website

图6 不同生长系数η时的电树枝分形维数

Fig. 6 Fractal dimension of electrical branche with growth coefficient η being altered

图7 电场分布分析

Fig. 7 Analysis of electric field distribution (a) Dielectric composites composed of filler particles and matrix; (b) Internal electric field distribution in dielectric composites Colorful figures are available on website

图8 不同介电常数时的电场及电位移场分布

Fig. 8 Electric field and displacement field distribution with different dielectric constant (a) Electric field distribution along AA' transversal; (b) Electric displacement field distribution along AA' transversal; (c) Electric field distribution along AA' transversal with dielectric constant of filler particles reduced by m times; (d) Electric displacement field distribution along AA' transversal with dielectric constant of filler particles reduced by m times Colorful figures are available on website

图9 添加不同无机填料含量的介电复合材料的击穿损伤形貌

Fig. 9 Breakdown damage morphologies of dielectric composites with different contents of inorganic fillers Colorful figures are available on website

图10 不同含量无机填料的介电复合材料与纯聚合物基体的损伤形貌量化对比分析

Fig. 10 Quantitative analysis of breakdown damage morphology between dielectric composite with different contents of filler particles and pure polymer matrix (a) Fractal dimension; (b) Damage path length

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